Centrifugal fan wheel

ABSTRACT

A centrifugal fan wheel and blade assembly is provided, including a center-plate, a side-plate, and a plurality of twopiece airfoil-type blades located between the plates, each blade having a tail-piece permanently secured between the plates, and a nose-piece removably secured between the plates for field replacement.

United States Patent [191 Hoffmann Dec. 24, 1974 CENTRIFUGAL FAN WHEEL 2,440,317 4/1948 Welsh 416/224 x 3,171,586 31965 A 416 18 [75] Inventor: Joseph NOW/00d 3,263,963 8/1966 11251116 et a1. 416/182 Mass 3,315,941 4/1967 Davies 416/224 Assignee: Westinghouse Electric Corporation, 3,398,883 Al'lByVltZ 4l6/224 Pittsburgh, Pa. 3,426,965 2/1969 Kullmg 416/224 [22] Filed: Oct 18, 1973 FOREIGN PATENTS OR APPLICATIONS 959,583 3/1957 Germany 416/186 M N 407,725 656,336 8/1951 Great Britain 416 224 52 U.S. c1 416/184, 416/186, 416/214, Primary ExaminerEverette Powell,

416/224 Attorney, Agent, or FlrmC. F. Renz [51] Int. Cl. F0411 17/16, F04d 29/30 [58] Field of Search 416/184, 186, 214, 224, [57] ABSTRACT 416/186 A A centrifu a1 fan wheel and blade assembly is pro- 'd d l d' l d l d l v1 e me u mg a center-p ate, a s1 e-p ate, an a p u- [56] References Clted rality of two-piece airfoil-type blades located between UNITED STATES PATENTS the plates, each blade having a tail-piece permanently 978,753 12/1910 Hurst 416/224 secured between the plates, and a nose-piece remov- 1,034,456 8/1912 Hurst ably secured between the plates for field replacement. 1,217,386 2/1917 Banner.. 1,327,812 1/1920 Exton 416/224 2 Claims, 4 Drawmg Flgllres FATENTEIJUEEZMSH Y SHEET 1 [IF 2 FIG. I.

BACKGROUND OF THE INVENTION This invention relates to centrifugal fan wheel blade assemblies.

The airfoil-type fan blades on a centrifugal fan wheel are extremely susceptible to wear in an erosive atmosphere. The deterioration of these blades has been remedied in the past by either pre-fitting the blades with wear liners or rebuilding the entire wheel at the factory. Since the blades are usually permanently affixed to the fan wheel, it is desirable to provide a blade assembly in which the worn part of the blades can be easily replaced without a substantial dismantlement of the fan wheel. Replacement of the entire blade often isnt necessary since it is the leading edge of the blade that is exposed to the full impact of the eroding particles entrapped in the moving gas stream, and it is usually the leading edge that first becomes worn and alters the airflow of the gas stream. Thus, it is desirable that the leading edges of the blades comprise removable nosepieces which can be replaced easily and conveniently in the field.

STATE OF THE PRIOR ART US Pat. No. 3,426,965 shows a centrifugal fan blade assembly which includes a removable frame. However, the nose-piece defining the leading edge of the blade is not removable nor is the tail-piece permanently secured to the fan wheel.

SUMMARY OF THE INVENTION This invention provides a fan wheel blade nose-piece assembly which may be easily replaced in the field. A plurality of airfoil-type fan blades are mounted between the centerplate of the fan wheel and the sideplate.

Each fan blade has two sections: a nose-piece and a tail-piece. The tail-piece is permanently secured between the center-plate and the side-plate and the nosepiece is removably secured between the center-plate and the side-plate. In the preferred form, the nosepiece is provided with an aperture, extending through the major axis of the nose-piece from the side-plate to the center-plate. Bolt means extend through this aperture to removably secure the nose-piece between the side-plates of the fan wheel. Screws may be located in both the tail-piece and the nose-piece to secure the skin of the tail-piece to the nose-piece.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of the centrifugal fan and blade assembly partially cut away to show the location of one of the blades.

FIG. 2 is an enlarged vertical section of one of the blade assemblies showing an exploded view of the assembled relationship of the removable nose-piece and the permanently affixed tail-piece.

FIG. 3 is a vertical section of the fan wheel andblade assembly showing the location of the fan blades between the center-plate and the side-plate, and the bolt means removably securing the nose-piece between the plates.

FIG. 4 is an enlarged view of the removable bolt means of FIG. 3.

DETAILED DESCRIPTION FIGS. 1 and 3 show a centrifugal fan wheel and blade assembly 1 having a center-plate l3 and side-plates l4 axially spaced from the center-plate. A plurality of airfoil-type blades 2 are shown mounted to the wheel and between the center-plate l3 and the side-plates 14a and 14b. The fan wheel 1 is symmetric about the center-plate 13, therefore, only the side of the wheel as shown will be discussed.

Referring also to FIGS. 2 and 4, each airfoil-type blade 2 of the blade assembly consists of two segments: namely a nose-piece segment 4 defining the leading edge of the blade when assembled, and a tail-piece segment 3 defining the trailing edge of the blade when assembled. It is preferred that the nose-piece 4 is removably secured to the skin of the tail-piece 3 by threaded fastening means 5 (i.e., screws); if desired, both the nose-piece 4 and the tail-piece 3 may be formed with aligned recessed apertures (not shown) to receive the threaded fastening means 5, and complementary flanges (not shown) to assist in pulling the skin surface of the tail-piece 3 flush with the surface of the nosepiece 4.

In the assembled relationship, the blade 2 is positioned in a desirable location between the plates with only the tail-piece 3 permanently secured (such as by welding) between the center-plate 13 and the sideplate 14. The nose-piece 4 is secured between the plates by the complementary arrangement of a thru bolt 6 and a central aperture 7 which extends through the major axis of the nose-piece 4 to receive the thru bolt as shown in FIGS. 1-4. This complementary arrangement comprises the only means of securing the nose-piece between the plates; yet it is easily removed if field replacement of the nose-piece is desired.

I claim:

1. A centrifugal fan wheel and blade assembly comprising, a center-plate, a side-plate axially spaced from said center-plate, a plurality of airfoil-type blades to be located between said center-plate and said side-plate, each of said airfoil blades having at least two segments including a nose-piece segment defining the leading edge of said airfoil in the assembled relation, said nosepiece segment being provided with an aperture extending longitudinally through the major axis of said nosepiece from the side-plate to the center-plate and a tailpiece segment defining the trailing edge of said airfoil in the assembled relation, means to permanently secure said tail-piece segment between said center-plate and said side-plate, and means to removably secure said nose-piece segment between said center-plate and said side-plate in the assembled relationship, wherein said removable securing means includes a bolt extending through said aperture and said centerand side-plates.

2. Apparatus of claim 1 wherein said nose-piece segment is removably secured to the skin of said tail-piece with threaded fasteners. 

1. A centrifugal fan wheel and blade assembly comprising, a center-plate, a side-plate axially spaced from said center-plate, a plurality of airfoil-type blades to be located between said center-plate and said side-plate, each of said airfoil blades having at least two segments including a nose-piece segment defining the leading edge of said airfoil in the assembled relation, said nose-piece segment being provided with an aperture extending longitudinally through the major axis of said nosepiece from the side-plate to the center-plate and a tail-piece segment defining the trailing edge of said airfoil in the assembled relation, means to permanently secure said tail-piece segment between said center-plate and said side-plate, and means to removably secure said nose-piece segment between said centerplate and said side-plate in the assembled relationship, wherein said removable securing means includes a bolt extending through said aperture and said center- and side-plates.
 2. Apparatus of claim 1 wherein said nose-piece segment is removably secured to the skin of said tail-piece with threaded fasteners. 